Design the distributed algorithms that keep systems correct under failure
Design Twitter Snowflake-style ID generation with time-ordering, no coordination, 64-bit IDs, and handling clock skew across data centers.
Design a locking service like ZooKeeper with Raft consensus, session management, watch notifications, fencing tokens, and split-brain prevention.
Design a Kubernetes-like scheduler with bin packing, gang scheduling, preemption, quota management, and multi-tenant fairness.
Design Jaeger/Zipkin-like tracing with span collection, tail-based sampling, trace assembly, and sub-1% performance overhead.
Design a CDC-based audit system with Debezium, Kafka streaming, compliance reporting (GDPR/SOX), and 7-year retention.